The current proposal is a competitive renewal which seeks continued support for ongoing studies which in the past 22 years have dealt with the physicochemical, immunologic and biosynthetic aspects of basement membrane macromolecules. The proposed studies will focus on structure-function relationships at the molecular level of two basement membrane macromolecules, namely, type IV collagen and laminin. Although, the ultrastructure of the type IV molecule has been well described, our knowledge of the macromolecular organization of basement membranes remains incomplete. Aim 1 will be an attempt to continue our studies of the ultrastructure of anterior lens capsule (ALC) using extraction pro- cedures that will yield molecules in different states of aggregation. In recent years we learned a great deal about the antigenic epitopes on basement membrane macromolecules that give rise to nephritogenic antibodies. Both the NC-1 and 7-S domains have amino acid sequences which react specifically with sera from patients with Goodpasture syndrome (GP) and post-streptococcal glomerulonephritis (APSGN). Aim 2 will be an attempt to determine the immunologic reactivity of synthetic peptides selected from specific peptide regions of the NC-1 and 7-S domains of type IV collagen chains. Our approach will involve the selection of antigenic regions from the newly described alpha chains by use of predictive programs for secondary structure and determination of immunoreactivity of the synthetic peptides with antisera to NC-1 and 7-S domains as well as sera from patients with a variety of immune mediated renal diseases. The binding of type IV collagen to cells and to other constituents of basement membranes allows for the normal organization of these structures and provides a mechanically stable support for cells in the basement membrane zone. Aim 3 will involve the study of the role of type IV collagen and its domains in cell adhesion and migration as well as their effect on neutrophil binding and activation. The discovery of laminin isoforms in normal tissues and their absence in solid tumors provides an opportunity to study structure-function relationships of specific laminin subunits. In Aim 4 we will study laminin gene expression and its regulation in normal and neoplastic cell lines and tissues and compare the biological activity of laminins synthesized by such cells and tissues.